Use of binocular camera (Linux)

The old demo program will call Rockchip's 3a algorithm to call the
mipi camera, but now these two cameras have their own 3a algorithm, so
there will be call errors when using the old demo program. To solve
this problem, we provide a demo of the v4l2 framework to call the
binocular camera:

Compile the demo code on the board：

   sudo apt-get update
   sudo apt-get install -y git libopencv-dev cmake libdrm-dev g++ librga-dev

   git clone https://github.com/T-Firefly/rkisp-v4l2.git

   cd rkisp-v4l2/
   cmake ./
   make

   sudo -u firefly DISPLAY=:0 ./rkisp_demo -c 300 -d /dev/video0 -w 640 -h 480
   or
   sudo -u firefly DISPLAY=:0 ./rkisp_demo -c 300 -d /dev/video5 -w 640 -h 480